This invention relates generally to opacity monitoring equipment and relates more particularly to a hood assembly for an opacity monitor.
The opacity monitoring equipment with which this invention is concerned is commonly utilized in connection with an industrial smokestack or chimney for monitoring the cleanliness of gases discharged through the smokestack or chimney. Such equipment commonly includes an opacity monitor comprised of a system of monitoring components fixedly attached to a back, or blower, plate which is, in turn, fixedly attached to the outside surface of the smokestack. An appropriate conduit connected in flow communication between the inside of the smokestack and the opacity monitor routes the smokestack gas to the monitor.
For protection of an opacity monitor from rain or other weather-related elements, a hood is positioned over the monitor so as to substantially cover the top, front and two opposite sides of the monitor and is held in place by appropriate connections to the blower plate. A hood of a conventional hood assembly has heretofor been connected to the blower plate adjacent an upper edge thereof to permit the hood to be pivotally moved about a horizontally-oriented pivot axis positioned adjacent the smokestack from a first, or lowered, condition at which the hood operatively covers the opacity monitor to a second, or elevated, condition at which the hood is generally positioned above the monitor. Movement of the hood to the aforedescribed second, or elevated, position permits operator access to the monitor.
A disadvantage associated with the aforedescribed connection between the hood and blower plate relates to the space necessary to pivot the hood between the aforesaid lowered and elevated conditions. A conventional hood is generally tall as measured from top to bottom for spanning the generally tall height of the blower plate when covering the opacity monitor so that as the hood is pivoted between the lowered and elevated conditions, the horizontally-oriented pivot axis confines the pivotal movement of the hood or, more specifically, the lowermost edges of the hood, along a relatively wide swing extending from the outside surface of the smokestack to a location positioned outwardly from and relatively remote of the smokestack surface. Hence, the movement of the hood between the lowered and elevated conditions requires a relatively large amount of space as measured along a horizontal path extending generally perpendicular to the outside surface of the smokestack. Because an opacity monitor is commonly mounted at a relatively high elevation upon a smokestack and approachable only by means of a platform or similar walkway attached to a side of the smokestack and positioned immediately beneath the opacity monitor, the aforedescribed hinged connection between a hood and blower plate requires that the hand railing associated with the platform to accommodate the relatively wide swing of the hood between lowered and elevated conditions. In particular, the railing must be spaced relatively far from the smokestack surface in the vicinity of the monitor to accommodate the swing of the hood and is generally much more costly to construct or modify than it would be if the railing need only be relatively close to the smokestack surface in the vicinity of the monitor or need not be modified at all.
Accordingly, it is an object of the present invention to provide a new and improved hood assembly for an opacity monitor circumventing the aforedescribed disadvantage associated with a conventional hood and its pivotal attachment to a blower plate.
Another object of the present invention is to provide such a hood assembly having a hood which requires little space as measured from the outside surface of a smokestack for moving the hood between lowered and elevated conditions.
Still another object of the present invention is to provide such a hood assembly wherein the hood is stability connected to an opacity monitor with which it is used during movement between the lowered and elevated conditions.
Yet still another object of the present invention is to provide such an hood assembly which is economical to manufacture and effective in operation.